Maximal Static Pressures and Lung Volumes in a Child with Guillain-Barré Syndrome Ventilated by a Cuirass Respirator

Abstract

Serial maximal static pressure and lung volume measurements were made in a child with Guillain-Barré syndrome and respiratory failure. The patient received successfully ventilatory support for seven weeks with the use of a cycled negative-pressure cuirass-type respirator obviating prolonged intubation and tracheostomy. The fall in VC preceded the loss of respiratory muscle strength (RMS) and lagged behind RMS in the return towards normal values. There was a disproportionate loss of lung volume (lowest VC, 220 to 250 ml, 11 to 12 percent of normal) as compared to maximal static pressures (lowest PImax, 60 cm H2O, lowest PEmax, 47 cm H2O). The disproportion was greater than that previously reported in adults. The greater loss in lung volume may be due to greater chest wall compliance in the child, resulting in less outward recoil of the chest wall and subsequently more microatelectasis with denervation of the chest wall musculature. Loss of lung volume resulted in a smaller surface area over which the respiratory muscles exerted their force. Thus, pressure being equal to force divided by surface area, could be relatively maintained and not reflect the extent of the loss of muscle force.